Heathland plant species composition and vegetation structures reflect soil‐related paths of development and site history

Abstract

QuestionsTo improve our knowledge on how environmental conditions determine the development of high‐value Calluna vulgaris heathland habitats, we studied the floristic and structural characteristics of heathland plant communities across North Germany and how they are influenced by edaphic, climatic and management factors. We ask how heathland development is related to these factors and what are the implications for conservation management and restoration.LocationNorth German Plain.MethodsWe collected 350 relevés in 18 dry Calluna heathland areas. Plant communities were classified using Isopam, and Redundancy Analysis (RDA) determined effects of environmental conditions. Potential pathways of development and the nature conservation status of the communities were identified on a multifactorial basis.ResultsWe found nine floristically and structurally distinct heathland plant communities. Heathland vegetation showed distinct patterns along Calluna age development stages and environmental conditions. Soil conditions and related effects of long‐term site history and recent management turned out to be the predominant factors influencing species composition and diversity, resulting in three potential heathland succession pathways. Mosaic‐like communities with particularly high taxonomic diversity and conservation value occurred on early‐successional inland dunes or as regeneration stage growing on nutrient‐poor sandy soils without humus accumulation.ConclusionsThe study reveals fundamental differences between historically farmed heathland in the oceanic Northwest and former military training areas mainly in northeastern Germany with consequences for restoration ecology. Present nature conservation criteria turned out to be insufficient in predicting habitat quality, as lichens are frequently disregarded. Our findings highlight the need for intense soil disturbance to maintain early‐stage soil conditions and a diverse Calluna growth‐phase composition, as these factors essentially determine species richness in lowland heaths.

The Calluna life cycle concept revisited: implications for heathland management

“…We examined a total of 445 Calluna plants in 352 plots of 25 m 2 , randomly placed by QGIS coordinate generation in 19 study areas across the North German lowlands (for location and details see Online Resource 1: Fig. 1, Tables 1 and 2; see also Schellenberg and Bergmeier 2020). Up to 8 representative plants were collected on each plot, two of each development phase (Online Resource 1: Table 3).…”

Ensuring the Long-Term Provision of Heathland Ecosystem Services—The Importance of a Functional Perspective in Management Decision Frameworks

“…Furthermore, this interaction may depend on Calluna life-stage and provenance (Meyer-Grünefeldt et al, 2016;Ibe et al, 2020). Future heathland management assessments should, therefore, include the generative rejuvenation capacity as a trade-off component which requires the presence of mineral soil horizons (Henning et al, 2017;Ibe et al, 2020;Schellenberg and Bergmeier, 2020;Walmsley and Härdtle, 2021).…”

The Regenerative Potential of Managed Calluna Heathlands—Revealing Optical and Structural Traits for Predicting Recovery Dynamics

“…For example, since the development of Calluna life-cycle phases is not uniquely classifiable after plant age [18,69], site specific environmental conditions and preceding management activities must be incorporated as population status indicator to evaluate the actual regenerative potential. This is particularly of utmost importance in continental dry heaths where seedling recruitment is low after mowing and burning [11,17,19] and thus the potential resprouting capacity needs to be evaluated beforehand for maintaining a vital habitat status of Calluna heathland.…”

“…Habitat management is crucial for the maintenance of Calluna heathlands since traditional forms of land use are neglected and a strong decline in habitat extent and degradation of habitat quality can be observed over the last decades [14,16]. In various years of fire and mowing management of European continental dry heaths, particularly on former military training areas, it has been found out that population-level recovery is dominated by resprouting from the stem base of Calluna individuals [17][18][19]. The dominance of resprouting can potentially contribute to the management goals regarding Calluna density, stand vitality and reproductive capacity if there is a relatively young population age structure (<15 years) affected [20,21].…”

“…Resprouting without regeneration over seedling recruitment leads to a gradual loss of vitality and density in Calluna stands which opens up the populations for ecosystem conversion such as grass invasion. As a consequence, it was suggested to occasionally remove the upper vegetation layer by sod-cutting in order to effectively promote germination which triggers the generation of diverse life-cycle phase patterns in Calluna heathlands [11,17,25]. Keeping this in mind, conservation managers need to carefully evaluate beforehand whether a potential management success can be ensured by the implementation of selected management measures.…”